BIO 122 Lecture Notes - Lecture 4: Phosphoglycerate Kinase, Pyruvate Dehydrogenase, Dihydroxyacetone Phosphate
Prior to Week 4 – Chapter 9 – Cellular Respiration
Know
• what redox reactions are
o know that glucose is oxidized to CO2 and O2 is reduced to water
• the difference between respiration (breathing) and cellular respiration, but that the two are inherently
connected
• what substrate-level phosphorylation is
o used by glycolysis and citric acid cycle
o produced by phosphorylation by enzyme-catalyzed
• what biochemical feedback means
• glucose
o used for glycolysis
o cell resp input
• ATP
o Releases energy
• NADH
o Electron carrier
• NAD+
o Reduced to make electron carrier
• FAD+
o Reduced to make electron carrier
• FADH2
o Electron carrier
• the 4 overall stages of respiration
o glycolysis
o pyruvate
o citric acid
o etc
• the 3 main phases of glycolysis and inputs and outputs
o glucose to glucose-6-phosphate
▪ by hexokinase
o glucose-6-phosphate to fructose-6-phosphate
o fructose-6-phosphate to fructose- 1,6 – bisphosphate
▪ by phosphofructokinase
o to glyceraldehyde 3-phosphate (G3P) and dihydroxyacetone phosphate (DAP)
o to 2 G3P
o to 1,3 biphosphoglycerate (1,3 BPG)
o to 3-phosphoglycerate (3PG)
▪ by phosphoglycerate kinase
o to 2-phosphoglycerate (2PG)
o to phosphoenolpyruvate (PEP)
o to pyruvate
▪ by pyruvate kinase
• that enzymes in glycolysis can be regulated to limit the rate of glucose oxidation
o hexokinase – if too much G6P is available, it will not proceed
o phosphofructokinase – if too much ATP is available, ATP allosterically inhibits PFK activity
• that pyruvate dehydrogenase removes CO2 from pyruvate, attaches coenzyme A, resulting in Acetyl-CoA
and NADH
• The citric acid cycle
o ultimately produces 2CO2, 1ATP, 3NADH and 1 FADH2 and oxaloacetate
• TCA cycle starts with oxaloacetate. Acetyl (coA removed) will get added to oxaloacetate to form citrate
o By citrate synthetase
• isocitrate dehydrogenase takes 6 carbon isocitrate and generates 5 carbon alpha-ketoglutarate and
releases CO2 and NADH
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